A polymer electrolyte fuel cell (PEFC) includes a catalyst layer serving as an anode (a fuel electrode) on one side of a polymer electrolyte membrane, a catalyst layer serving as a cathode (an air electrode) on the other side thereof, and gas diffusion layers bonded to the outsides of the catalyst layers. Each catalyst layer is formed of a supported catalyst where catalyst particles containing a precious metal are highly dispersed and supported on nano-level support particles.
By supplying hydrogen serving as a fuel to the anode and oxygen or air to the cathode, power is generated in accordance with Reaction Formulas (1), (2) below.Reaction at anode: 2H2→4H++4e  (1)Reaction at cathode: O2+4H++4e−→2H2O  (2)
Technologies relating a catalyst for fuel cells that generate power by causing the above reactions have been disclosed in, for example, Japanese Unexamined Patent Application Publication Nos. 2006-026586, 2004-363056, 2003-092114, 2005-174835, and 2008-155111, Japanese Patent Nos. 5322110 and 5515019, Takeoh Okanishi, Toshiaki Matsui, Tatsuya Takeguchi, Ryuji Kikuchi, Koichi Eguchi, Applied Catalysis A, 298, 2006, pp. 181-187, and Naoto Kamiuchi, Tomohiro Mitsui, Nobutada Yamaguchi, Hiroki Muroyama, Toshiaki Matsui, Ryuji Kikuchi, Koichi Eguchi, Catalysis Today, volume 157, issues 1-4, Nov. 17, 2010, pp. 415-419. Japanese Patent No. 5515019 proposes the use of a chain-structured oxide and/or nitride support as a support for Pt and Pt-alloy catalysts. Japanese Patent No. 5515019 states that a chain-structured Pt and Pt-alloy catalyst supporting oxide and/or nitride support has improved durability at high potential and allows for the expression of catalytic activity equivalent to that of a Pt-supported carbon catalyst.